Windows servers cannot be automatically deployed to. This is by design.

To prohibit accidental deployment to servers when synchronized with Active Directory the feature to 'Install Sophos Security Software Automatically' will not work.

What To Do

Only workstations (computers not running a server operating systems) can be protected automatically when imported to the console via an Active Directory synchronization. Servers must be protected using the Protect Computers Wizard (see the section 'Installing endpoint software' in the Sophos endpoint deployment guide) or by running Setup.exe on the server locally.

For further information on the AD sync feature see the help manual for your version of console.